#include <stdio.h>
#include <string.h>

int main() {
    char str1[20] = "Hello";
    char str2[20] = " World";
    
    // 计算字符串长度
    printf("Length of str1: %d\n", strlen(str1));
    
    // 连接字符串
    strcat(str1, str2);
    printf("Concatenated string: %s\n", str1);
    
    // 复制字符串
    strcpy(str2, str1);
    printf("Copied string: %s\n", str2);
    
    return 0;
}